Refrigeration apparatus with air flow bypass means



Jan. 23, 1968 R. D MAXWELL 3,364,696

REFRIGERATION APPARATUS WITH AIR FLOW BY-PASS MEANS Filed July 28, 1966FIG 2 I N V [5N TOR. RICHARD D. MAXWELL ATTORNEY United States Patent3,364,696 REFRIGERATION APPARATUS WITH AIR FLOW BYPASS MEANS Richard D.Maxwell, edar Rapids, Iowa, assignor to Amalia Refrigeration, Inc.,Middie Amana, Iowa,

a corporation of Delaware Filed July 28, 1966, Ser. No. 568,547 3Claims. (Cl. 62-414) ABSTRACT OF THE DISCLOSURE An air circulation anddistribution system for a combination freezer'refrigerator employing afinned coil type evaporator through which air is circulatedlongitudinally of the fins. Undue frosting of the leading edges of theevaporator fins, owing to the circulation of large quantities of moistair from the refrigerator compartment, is prevented from dangerouslyreducing air flow through the evaporator by means of bypass return airopenings downstream of the main return air openings which permit thereturn air to bypass the leading edges of the fins. The main and bypassreturn air openings are sized so that the latter do not becomesubstantially effective until the leading edges of the fins become frostclogged.

Background 0] the invention The combination freezer-refrigerator inwhich the refrigerator and freezer compartments have separate accessdoors is considered a substantial improvement over a single largecompartment unit containing a small freezer compartment. Early models ofsuch two-door combinations typically had a separate evaporator for eachcompartment and no forced air circulation. Subsequent improvements andmodifications led to the adoption of an arrangement in which therefrigerated air was forcibly circulated throughout the refrigerator andfreezer compartments and over the evaporators. In such arrangementsfrost tends to form on the evaporators, which frost may be periodicallyremoved by employing a reversible refrigeration system or by electricheating elements embedded in the evaporators. The simplest and thus themost economical and reliable form of periodic defrosting is thatperformed on a fixed time-cycle basis. However, a disadvantage of thefixed defrost cycle when finned type evaporators are used is that frostmay build up on the fins, especially on those of the evaporator of therelatively moist refrigerator compartment, between defrost cycles to thepoint where the flow of air through the evaporator is substantiallyreduced. This is particularly frigeration components at a minimum.

Summary 07 the invention The invention herein provides an arrangementwhereby it is virtualy impossible for the air flow to become blocked byreason of frost build-up on the evaporator fins. This is accomplished ina very simple and inexpensive manner, in great contrast to other methodsof dealing with the problem, by providing additional or bypass openingsleading the return air into the evaporator downstream from the mainreturn opening. The bypass openings are sized and 3,364,696 PatentedJan. 23, 1968 ice located so that the return air will normally not flowthrough them but rather substantially all through the main returnopening as long as frost build-up does not substantially impede the flowthrough the evaporator.

The details and features of the invention will be more readily apparentfrom a consideration of the-following description of a preferred formthereof, being the best mode known of carrying out the invention.

Brief description of the drawings FIG. 1 is a front elevational view ofa freezer-refrigerator combination, the doors being omitted and aportion of the liner of the freezer compartment being broken away toshow some of the refrigeration components;

PEG. 2 is a vertical sectional view taken along the line 22 of FIG. 1through the freezer compartment; and

FIG. 3 is a sectional view through a portion of the freezer compartmenttaken along the lines 33 of FIG. 1 and illustrating the duct arrangementby which the air is circulated into the freezer and refrigeratorcompartment.

Description of a preferred embodiment The freezer-refrigeratorcombination shown in the drawings is one in which the refrigerator andfreezer compartments are side-by-side. The cabinet, indicated generallyby the reference numeral 10, has a central vertical partition 12 whichseparates the cabinet into a refrigerator compartment 14 and a freezercompartment 16. Separate doors (not shown) are provided to close therespective compartments.

The cabinet 10 includes an outer cabinet wall 17 and a pair of innerliners spaced therefrom by suitable insulation, as is Well known tothose skilled in the art, to form the refrigerator compartment 14, andthe freezer compartment 16, respectively, and the partition 12. Therefrigerator liner provides a back wall 18, side walls 20, a top wall 22and a bottom wall 24. Similarly, the freezer liner provides a back Well26, side walls 28, a top wall 30, and bottom wall 32.

As best seen in FIG. 2, a vertical panel 34 is spaced forwardly of theback Wall 26 of the freezer to provide a compartment in which anevaporator 36 is positioned. Evaporator 36 is of the finned type and isdisposed upright with its fins extending vertically. An accumulator 38is horizontally disposed below the evaporator 36, and the remainingmajor refrigeration components, including a compresser 40, a fan 41 anda condenser 42 are located beneath the bottom wall 32 of the freezercompartment which is upwardly shaped at its rear to provide spacetherefor.

In order to circulate the air so that return warm air from thecompartments 14 and 16 is cooled by passing between the fins ofevaporator 36, a fan 44 is located between the vertical panel 34 andback wall 26 of the freezer compartment 16. The fan 44 is located aboveand downstream from the evaporator 36 and discharges air upwardly into apassageway 47 formed by the upper end of the vertical panel 34 and theback wall 26 of the freezer compartment. In order to provide fordischarge of cool air into the freezing compartment 16, the side edgesof the vertical panel 34 above the fan 44 are spaced inwardly from theside walls 28, and are preferably turned rearwardly, as best seen inFIG. 3.

To provide for circulation of air into the refrigerator compartment 14,a horizontal molded duct 48 is disposed in the insulation between theback wall 26 and the outer cabinet wall 17 and connects the upper end ofthe passageway 47 with the refrigerator compartment 14. The duct 48opens into the refrigerator compartment 14 through a thermostaticallycontrolled damper 50 which regulates the size of the discharge opening51 into the refrigerator a compartment 14. A thermostat (not shown) onthe rear of the diffuser plate 52 is responsive to the air temperaturein the refrigerator compartment and controls operation of the damper 50.A thermostat (not shown) in the freezer compartment 16 controlsoperation of the compressor 40 and fans 41 and 44 to regulate thetemperature in the latter compartment. Preferably a manual control 54 isprovided on the front face of diffuser 52 by which the extent of themovement of damper 50 may be controlled.

The warm air returning to the evaporator 36 from the refrigeratorcompartment 14 passes through a lower duct 56 formed in the partition 12between the back wall 26 of the freezer compartment and the panel 34 ata point below the evaporator 36. Return air from the freezer compartment16 is circulated back to the evaporator 36 by means of an opening 58formed by termination of the vertical panel 34 short of the bottom wall32 of the freezer, as shown in FIG. 2. Thus, the return air from bothcompartments 14 and 16 conjoin for passage up through the evaporator 36.

Defrosting of the evaporator 36 is accomplished by electric heatingelements (not shown) embedded in the evaporator and energized by a timerhaving a fixed cycle of eight hours. Defrost systems of this and othertypes are well known to those skilled in the art and as they form nopart of the invention herein are not disclosed in any further detail.

As mentioned, in the case of defrost systems that operate on a fixedtime cycle, frost build-up on the fins of evaporator 36 may occurbetween defrost cycles to such an extent that the flow of air across theevaporator will be substantially blocked. As is well known to thoseskilled in the art, such frost build-up readily occurs first and mostheavily on that portion of the evaporator fins initially contacted bythe return air from the freezer and refngerator compartments duringperiods of frequent door openings, especially of the latter compartment.Inasmuch as most moisture is removed from the air by the initialportion, that is to say, the lower ends of the fins of the evaporator36, further cooling of the air by passage up through the remainingportion of the evaporator fins causes comparatively little frostformation. In order to avoid the possibility of air circulation beingimpaired by the formation of excessive frost on the lower end ofevaporator 36, one or more openings 60 are provided in panel 34 of thefreezer compartment 16. These openings 60 provide a bypass orsupplementary inlet for circulatron of air from the freezer compartment16 positioned above the lower portion of the evaporator 36 where heavyfrosting may occur. The openings 60 are of such a size and theirposition is such that return air from the freezer compartment 16 willnormally pass through the much larger main opening 58 and thus throughthe entire length of the evaporator 36. The openings 60 thereforeprovide temporary circulation of the air in the event of frost blockageof the lower end of the evaporator 36 until such frost can be removedduring the next defrost cycle. The bypass openings 60 thus provide avery simple solution to the problem concerned without the necessity, forinstance, of dividing the evaporator into separate portions for therefrigerator and freezer return air, or of any of the other much moreelaborate and costly methods employed for the purpose by the prior art.

Having thus described the invention, it will be apparent to thoseskilled in the art that various revisions and modifications can be madein the particular embodiment shown without departing from the spirit andscope of the invention. For example, it will be obvious to those skilledin the art that the principles of the invention can be utilized in topand bottom mount freezer-refrigerators as well as the side-by-side unitillustrated herein. Thus, all

revisions and modifications to the specific illustrated embodiment shownherein as are obvious to those skilled in the art are to be includedwithin the scope of the following claims.

I claim:

1. In a combination freezer-refrigerator having a cabinet defining arefrigerator compartment and an adjacent freezer compartment separatedby a partition wall, a refrigeration system including an evaporator ofthe finned coil type to cool air circulated therethrough, and a forcedair circulation system having an air passageway which includes a wall ofone of said compartments, said evaporator being disposed in saidpassageway so that said air passes between and generally longitudinallyof the fins of said evaporator, said passageway terminating in an airoutlet opening into said refrigerator compartment and an air outletopening into said freezer compartment, said passageway also having amain return air inlet opening thereto upstream of one end of the fins ofsaid evaporator and communicating with both of said compartments, theimprovement comprising one or more air bypass openings in said airpassageway wall from said one compartment and disposed to communicatewith said passageway downstream of said end of the fins of saidevaporator, each of said bypass openings being sufficiently smallrelative to said main inlet openings so that return air normally flowssubstantially only through said main inlet openings into said passagewayuntil air flow from said main inlet openings through said end of thefins of said evaporator becomes substantially reduced owing to frostbuildup between the fins at said end thereof.

2. The air circulation system of claim 1 in which said passagewayextends vertically along a wall of one of said compartments and saidinlet openings are at the lower end of said passageway, said bypassopenings being located above said inlet openings and providing for thecirculation of air over all but the lower end portion of the fins ofsaid evaporator.

3. The air circulation system of claim 2 in which said compartments arelocated side-by-side and separated by a vertical partition, saidpassageway being formed between the rear wall ofsaid freezer compartmentand a panel spaced forwardly thereof, said inlet opening from saidfreezer compartment to said passageway being disposed adjacent thebottom of said compartment below said evaporator and a lower edgeportion of said panel. said outlet opening into said freezer compartmentfrom said passageway being formed along the upper edge portions of saidpanel, a fan located in said passageway between said evaporator and saidoutlet effective to move air through said inlet, said evaporator andsaid outlet, a laterally extending air supply duct communicating withsaid passageway adjacent said outlet to said freezer compartment andterminating at said outlet to said refrigerator compartment, a laterallyextending air return duct communicating with said inlet opening of saidrefrigerator compartment and terminating adjacent said inlet opening ofsaid freezer compartment to said passageway, said bypass openings beingdisposed in said panel, and means disposed adjacent said outlet to saidrefrigerator compartment effective to control the quantity of airadmitted thereto.

References Cited UNITED STATES PATENTS 2,152,291 3/1939 Starr 624192,495,626 1/1950 Booth 624OS 3,122,005 2/ 1964 Constantini 624193,137,146 6/1964 Wallenbrock 62-414 3,164,970 l/1965 Hubacker 62-187 XWILLIAM J. WYE, Primary Examiner.

